Scan pattern generator convertible between multiple and single line patterns

ABSTRACT

An arrangement for and a method of reading bar code symbols on a target to move a light beam emitted by a light source in a multiple line, scan pattern during a scan period in a first operational mode. Upon selection of a second operational mode by a user, a controller intermittently operates and energizes the light source to emit the light beam for a working time period which is less than, and a fraction of, the scan period to generate a single scan line across the symbol.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.09/231,396, filed Jan. 13, 1999, now U.S. Pat. No. 6,247,647, which is acontinuation-in-part of U.S. patent application Ser. No. 08/924,849,filed Sep. 5, 1997, now U.S. Pat. No. 6,102,293, which is acontinuation-in-part of U.S. patent application Ser. No. 08/381,515,filed Feb. 1, 1995, now U.S. Pat. No. 5,793,032, which is acontinuation-in-part of U.S. patent application Ser. No. 08/294,845,filed Aug. 29, 1994, now abandoned; and a continuation-in-part of U.S.patent application Ser. No. 08/068,025, filed May 28, 1993, nowabandoned; and a continuation-in-part of U.S. patent application Ser.No. 07/884,734, filed May 15, 1992, now abandoned, and acontinuation-in-part of U.S. patent application Ser. No. 07/246,382,filed May 20, 1994, now U.S. Pat. No. 5,410,140, which is a continuationof U.S. patent application Ser. No. 08/073,995, filed Jun. 9, 1993, nowabandoned, which is, in turn, a continuation of U.S. patent applicationSer. No. 07/787,458, filed Nov. 4, 1991, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to optical scanners for reading indicia ofvarying light reflectivity, and in particular to minimizing power usageand improving the aiming of such scanners.

2. Description of the Related Art

Various optical readers and optical scanning systems have been developedheretofore for reading indicia such as bar code symbols appearing on thelabel or on the surface of an article.

The symbol itself is a coded pattern of indicia comprised of, forexample, a series of bars of various widths spaced apart from oneanother so bound spaces of various widths, the bars and spaces havingdifferent light reflecting characteristics. The readers in scanningsystems electro-optically transform the graphic indicia into electricalsignals, which are decoded into alphanumeric characters that areintended to be descriptive of the article or some characteristicthereof. Such characteristics are typically represented in digital formand utilized as an input to a data processing system for applications inpoint-of-sale processing, inventory control and the like. Scanningsystems of this general type have been disclosed, for example, in U.S.Pat. Nos. 4,251,798; 4,369,361; 4,387,297; 4,409,470; 4,760,248;4,896,026, all of which have been assigned to the same assignee as theinstant application. As disclosed in the above patents, one embodimentof such scanning systems includes, inter alia, a hand held, portablelaser scanning device supported by a user, which is configured to allowthe user to aim the scanning head of the device, and more particularly,a light beam, at a targeted symbol to be read.

Such prior art hand held devices generally incorporate a light-receivingmodule which receives the light that has been reflected from the barcode symbol and determines, from the reflected pattern, the sequences ofbars and spaces within the symbol. The unit may also incorporatedecoding circuitry to decode the received information and to recover theunderlying data (for example the alphanumeric data) which the bar codesymbol represents.

It may in some circumstances be disadvantageous for the light generatingand emitting module to be housed within the same unit as thelight-receiving module and the decoding circuitry. In the first place,locating everything within the main housing requires that the bar codeto be read is positioned so that most or at least a substantialproportion of the reflected light returns to the unit along the samepath as the emitted light. It might not always be convenient for a userto position the bar code reading and/or the bar code so that the lightis reflected back along the same path in that way. Secondly, locatingeverything within the same unit means that the unit has to be physicallyrather large and relatively heavy. Users may not find it easy to operatefor long periods.

In the field of laser pointers, it is known to provide small hand heldunits which users can use at conferences, seminars or the like forpointing purposes. The visible spot of the laser beam, when shone onto ascreen, indicates to the audience the point of interest, and enables thelecturer to dispense with the traditional physical pointer. Althoughmodern laser pointers are relatively small and compact, theynevertheless still have to be grasped in the hand of the lecturer, whichnaturally restricts the lecturer's user of that particular hand.Typically, the laser pointer has to be put down every time the lecturerwishes to do something else, such as to turn over a page in his or hernotes, or to operate an overhead projector.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention there is providedan optical system for and a method of reading bar code symbols on atarget by moving a laser beam directed toward the target in a scanacross the symbol during a scan period that commences and ends atopposite scan end-limiting positions, respectively, of the scan. Powerusage of the system is minimized by intermittently operating andenergizing a light source during the scan period over a duty cycle priorto reading the symbol, to emit the laser beam for a working time periodwhich is less than, and a fraction of, the scan period. The intermittentand cyclical nature of energizing the light source produces multipleimages of the light beam on the symbol to visually enhance the aiming ofa hand-held scanner at the symbol.

The invention may be carried into practice in a number of ways, andseveral specific embodiments will now be described, by way of example,with reference to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1a and 1 b depict a portable optical scan system in accordancewith a first embodiment of the present invention;

FIG. 2 illustrates schematically the ring unit and the wrist unit shownin FIGS. 1a and 1 b;

FIG. 3 depicts a portable optical scan system in accordance with asecond embodiment of the present invention;

FIG. 4 depicts a laser pointer in accordance with a third embodiment ofthe present invention;

FIG. 5 shows details of the laser pointer of FIG. 4;

FIG. 6 illustrates the triggering mechanism which may be used with thelaser pointer of FIG. 4, or with either of the portable optical scansystems of FIGS. 1a, 1 b, or FIG. 3;

FIG. 7 illustrates a hand-held laser pointer/laser scanner of anotherembodiment;

FIG. 8 shows schematically yet a further embodiment in which a band forsecuring a pointer or scanner to the user's body comprises a flexiblebattery;

FIG. 9 represents a practical embodiment of the device shown in FIG. 8;

FIG. 10 shows a storage box for use with the portable optical scansystem of FIG. 1a;

FIGS. 11a and 11 b are schematic representations of laser beam scanningpatterns as is known in the prior art;

FIGS. 11c, 11 d and 11 e are schematic representations of laser beampulsing patterns according to the present invention;

FIG. 12a is the timing diagram of one embodiment of a laser beam pulsingpattern corresponding to FIG. 11c;

FIGS. 12b and 12 c are timing diagrams of other embodiments of the laserbeam pulsing pattern;

FIG. 12d is a timing diagram of another embodiment of the laser beampulsing pattern;

FIG. 13 is a block diagram of a system relating to the timing diagram ofFIG. 12d;

FIG. 14 is a perspective view of a portable scanner;

FIG. 15 is a perspective view of a scan line generator mounted in thescanner of FIG. 14; and

FIG. 16 is a part-sectional, part diagrammatic view of part of thegenerator of FIG. 15 and its control circuitry.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1A shows a portable optical scan system in accordance with a firstembodiment of the present invention. An optical scan module 1 isdetachably mounted on a single finger of a user 3 using a ring-shapedmounting. The detachable mounting may be of any number of conventionaltypes suitably adapted for its ease of use for the desired application.For example, a ball and flexible socket mounting, or a slide mountingcould be used. Other mountings with movable restraining members mightalso be used.

In addition to the optical scan module 1, the user 3 wears a firstperipheral module 7, on the wrist, and a second peripheral module 9 onthe other arm. As will be clear from the Figure, the scan module 1 emitsa scanning laser beam 10 which the user directs towards a bar codesymbol 13 to be read. The bar code symbol may be printed on or otherwiseattached to an article 11, details of which the user 3 wishes to obtainfor example for inventory or for sale purposes. The scanning beam 10 isreflected from the bar code symbol 13, and the reflected light 12 isdetected by the first peripheral module 7.

FIG. 1B illustrates a variant of the embodiment of FIG. 1A in which thereflected light 12 returning from the bar code symbol 13 is detected bya peripheral module 7′ which is secured to the user's clothing. In thevariant shown, the peripheral module comprises a detector which isclipped onto the breast pocket of the user's shirt. Other arrangements(not shown) could of course be envisaged, in which the peripheral module7′ is secured to or forms part of other articles of clothing.

FIG. 2 illustrates schematically the internal features of the scanmodule 1 and the first peripheral module 7. The module 1 incorporates adevice for generating and scanning the light beam 10, desirably avisible laser diode (VLD) 1 a, having a driver 1 b. Scanning of the beam10 is achieved by means of a scan element 1 c, and a scan element driver1 d. Power is provided by means of a small battery 1 e.

The first peripheral module 7 comprises a photodetector 7 e and receivercircuitry 7 d which are together arranged to detect the returning lightbeam 12. The output from the receiver circuitry is passed to a decoder 7a which is arranged to reconstitute the alphanumeric information whichthe bar code symbol 13 represents. The first peripheral module may alsoinclude a keyboard and/or display 7 c along with other possible features7 g such as for example a time display so that the module 7 doubles asan ordinary watch when it is not in use as part of the optical scansystem. A radio frequency (RF) or other wireless transmitter 7 b, alongwith a battery pack 7 f or other power supply completes the unit.

In use, the decoded information emanating from the decoder 7 a is passedby wireless link from the radio 7 b to the second peripheral module 9which is located on the other arm or wrist of the user. The radiotransmitter 7 b could be a transceiver which is also capable ofreceiving signals from the second peripheral module 9 or from a separatebase station 15.

The second peripheral module 9 incorporates a radio receiver 9 a and aradio transmitter 9 b for communicating with the first module 7 and/orwith the base unit 15. Typically, the respective transmissionfrequencies will be different. The second peripheral module 9 furtherincludes digitizing and processing circuits 9 c which convert thetransmitted analog signal to a digital signal and decode the signal in aconventional, manner. An indicator light, beeper or audio transducer 9 dsignals the user when the decoding has been satisfactorily accomplished.Such notice could also or alternatively be provided by informationdisplayed on a display unit 9 e. A memory storage device 9 h is alsopreferably included for temporary storage of the decoded data. A keypad9 f and/or touch screen may be used for inputting data to the system. Abattery 9 j is provided to supply power to the secondary peripheralmodule. Alternatively, or in addition, power may be supplied via anexternal lead 17 from a separate power supply 19 which is secured to thebody of the user, for example on a belt 21.

Depending upon the preference of the user, the second peripheral modulecould be worn on the right arm, or wrist, like a watch (and in fact, mayfunction as a watch) and the optical scan module 1 and the firstperipheral module on the left arm or wrist. In an alternative embodiment(not shown) the second peripheral module 9 could be dispensed with, withall the features of that unit instead being incorporated within thefirst peripheral module 7. This would of course be expected to make thefirst peripheral module much larger than is shown in the drawing.

It will be noted that in the arrangement shown in FIGS. 1A and 1B, thereis no cable or other physical connection between the optical scan module1 and either of the first or second peripheral modules. This improvesthe wearability of the system, and the likely user acceptance. It isalso rather safer, since the lack of wires means that there is less toget caught as the user moves around, perhaps undertaking a variety ofdifferent tasks while wearing the devices shown.

In a variation of the embodiment described above, the scan element 1 cand the scan element driver 1 d may be omitted from the optical scanmodule 1, so that the beam 10 is essentially a fixed beam. With such anarrangement, the user would then physically move his or her hand or arm,thereby manually scanning the beam 10 across the bar code symbol 13.Such an arrangement has the advantage that the module 1 can be reducedin size and in weight, not only by elimination of the mechanical andelectronic scanning features, but also because the battery 1 e maysubstantially be reduced in size. A suitable module for use with thisvariation is illustrated in FIGS. 5 and 6, which will be described inmore detail below.

A second embodiment of the second invention is shown schematically inFIG. 3. In this embodiment, the light 12 which is reflected from the barcode symbol 13 is detected by a separate detector unit 70 whichcomprises a fixed bank of photodetectors 72 which look down onto thesurface of the article 11 so as to detect the reflected light. Thedetector unit could be mounted to a stand 74 which is positionedadjacent a conveyor 76 along which the item 11 is passing.Alternatively, the detector unit 70 could be mounted in or secured to acash register, could be mounted to the ceiling, or may be suspended fromthe ceiling by a cable similar to a hanging lamp, or could be mountedwithin a tunnel which surrounds or at least partially surrounds theconveyor.

In this embodiment, the optical scan module 1 is preferably the same asthe scan module illustrated in FIGS. 1 and 2, with or without the scanelement 1 c and the scan element driver 1 d. If these are not providedwithin the module, the user has to manually scan the beam 10 across thebar code symbol 13 to be read. As a further alternative (not shown) ahand held pointer or hand held scanner could instead be used, but ineach case the detectors are fixedly mounted over the scanned surface.

In those cases in which the optical scan module 1 does not incorporate abeam scanning mechanism, the module 1 effectively becomes a ring-mountedlaser pointer. Such a pointer may, as previously described, be used forscanning applications merely by scanning the beam manually across theindicia to be detected, and providing separate detectors elsewhere,either fixedly mounted or secured to the body of the user, which detectthe reflected beam. However, a laser pointer of this type is notnecessarily restricted to scanning applications, and as may be seen fromFIG. 4 the laser pointer could instead be used at lectures, seminars,meetings and so on, or indeed at any type of public presentation.

Reference should now be made to FIGS. 5 and 6 which illustrate certainpreferred features of the laser pointer. The embodiment shown in FIGS. 5and 6 is equally applicable both to the application of FIG. 4 and theapplication of FIGS. 1A, 1B and 2.

The laser pointer 1 comprises a ring or shank portion 102, adapted to beworn on the finger of the user, to which is secured an upper housingportion 100. Within the housing is a battery which provides power to avisible laser diode (VLD) or other light source. The VLD is mounted to ametal holder/heat sink. Light generated from the VLD passes through anoptical system comprising a plurality of lenses, out through an exitwindow 112. The optical system preferably provides that the beam iscollimated or at least quasi-collimated. Electronic circuitry isprovided which maintains the laser output at a predetermined level, andalso acts as a trigger mechanism.

A trigger button 104 is provided on one side of the ring 102, where iscan be actuated by the user's thumb. In this way, the user can easilyswitch the laser beam on and off.

Another alternative and/or additional switching mechanism may beprovided by means of a separate ring which is attached to the user'smiddle finger and which is secured to the ring by means of a cord. As isshown in FIG. 6, the user may operate the device by flexing the middlefinger, and so pulling on the cord. This could be done either by bendingthe middle finger with respect to the index finger, or by pulling themiddle finger away from the index finger.

A device of this sort is both easy and convenient for a lecturer towear, and it also allows free use of the hand at all times. Because thering is preferably mounted to the index or forefinger, pointing accuracyis likely to be increased.

An alternative and/or additional switching mechanism may be provided bythe use of a limited range proximity sensor. Reference is made to U.S.Pat. No. 5,280,162 which is hereby incorporated by reference, asdescribing “object sensing” or proximity sensing technology in a barcode reader. By appropriate setting of threshold signals in the circuitsof such a system, the sensor may be made to trigger by a movement of thethumb, or by a more distant object embodiment of a “self triggering”mode which will be described in connection with FIGS. 11 and 12 in moredetail. Another embodiment utilizes a very small range proximity sensor,so that the unit will not be triggered by a distant target, but only theuser's thumb. In that embodiment, there is a very limited rangeproximity embodiment which provides a limited range proximity.

A sensor is located on the front or side surface of the ring 102. Whenthe user wishes to turn the unit on, a slight movement of the thumbcloser to the index finger will switch the unit on, thus avoiding theeffort required for the thumb to press a trigger switch.

FIG. 7 illustrates, schematically, a hand-held laser pointer 200 whichis capable either of providing a fixed laser beam, for pointing purposesor a scanning laser beam. Whereas a fixed laser beam generates a pointor dot, that can be aimed at a screen, a scanning beam generates a lineor a circle. This is especially convenient if the user wishes tounderline or to circle a sentence or a figure that is being pointed to.

The pointer shown in FIG. 7 incorporates a hand-held body 202, having amanually actuable multi-positioned switch 204. Inside the body 202 thereis a short wavelength VLD (visible laser diode) 206 which directs a beamonto a small, micro-machined mirror 208. This deflects the beam out of awindow 210 in the housing, thereby providing a pointing beam 212. Ascanning element 214 is provided for selectively oscillating the mirror208, thereby causing the beam 212 to be scanned.

In a first position of the switch 204, the laser diode 206 is switchedoff, and no beam is produced. In a second position, the laser diode isswitched on and is reflected from the stationary mirror 208, therebyproviding a fixed pointing beam 212. In a third position of the switch,the scanning element 214 is actuated, causing the beam 212 to bescanned, thereby generating a visible line on the surface that is beingpointed to. In the preferred embodiment, the scanning is in onedimension so that the resultant line on the screen is straight. In analternative embodiment, however, the scanning element 214 could causethe beam 212 to be scanned in two directions, thereby forming anydesired type of lissajous, such as a circle, on the screen. More complexscanning arrangements could also be envisaged, so that for example theimage projected onto the screen is a square or other desired figure.

If the trigger 204 is a multi-position trigger, the device could providea projected straight line in one position of the trigger, and aprojected circle in another position. Different positions of the triggercould also provide different lengths of line and/or different sizes ofcircle or other images that are being projected.

Scanning of the beam 212 of course reduces the visibility of the imagewith respect to the visibility of the dot generated by a fixed beam. Tocompensate, the laser output power is increased according to theposition of the trigger 204.

Instead of being hand-held, the device shown in FIG. 7 may be built intoa ring, and in particular it may be built into any one of the rings thathave previously been described. Naturally, in such a case, the trigger204 will be replaced with an appropriate trigger or switch on the ringitself. For example, if the arrangement of FIG. 7 is built into the ringshown in FIG. 6, the trigger 204 is merely replaced by the triggerbutton 104 (FIG. 5) or the cord 114 (FIG. 6). It will of course beappreciated that, where appropriate, the button and/or cord may bemulti-position. Alternatively (not shown) there may be several separateswitches, one of which for example produces a fixed beam and another ofwhich produces a scanning beam.

Batteries for wearable devices of the types which have already beendescribed typically occupy a significant proportion of the device'svolume, and additionally contribute to its weight. Where substantialpower is required, such as for example the devices illustrated in FIGS.1 to 3, a separate battery pack 19 is often the most convenient way toprovide the power that is needed. However, in a variation of theembodiments previously described, power may instead or in addition beprovided by a thin flexible battery which forms part of the band thatwraps around the arm, wrist or finger of the user. Specifically, in FIG.1A the wrist band 306 could be such a battery, as could be the arm bands302 or 304. In FIG. 5, the ring 102 could be a battery.

Preferably, the battery is of the lithium polymer rechargeable type,which is simply cut into the appropriate shape. Such batteries mayprovide sufficient power, on their own, for operation of some devices;in other cases, they may be used as an auxiliary battery, therebyreducing the size of the additional cells that may be necessary.

FIG. 8 illustrates the concept in schematic form. A flexible batterystrip 404, preferably a lithium polymer battery, is formed into a ringshape and is attached to a scanner and/laser pointer 402. Depending uponthe size of the device, the band 404 may fit around a finger, a wrist oran arm of the user.

FIG. 9 illustrates a practical embodiment in more detail. A flexiblebattery strip 408 is attached to two circularly-shaped snap springs 418and 420. One snap spring 418 is attached to the positive batteryterminal, and the other 420 to the negative battery terminal. At one endof the spring 418 there is a contact portion 410, while at the oppositeend of the other spring 420 there is a similar contact portion 412.These fit into corresponding grooves 414 and 416 in the lower surface ofthe scanner/laser pointer 406, thereby providing the necessaryelectrical power.

The exact shape and configuration of the battery and the contacts is notof course critical. In the embodiment shown in FIG. 9, the springs 418and 420 could be in the form of thin, sprung wires. Alternatively, theycould take the form, of flat leaf springs, which extend out of the planeof the diagram. In the first case, the scanner/laser pointer 406 isprovided with sockets 414 and 416 in the form of blind bores whichreceive the contact portions 410 and 412. Alternatively, where thesprings take the form of leaf springs, the contact portions 410 and 412may simply be slid into appropriate grooves 414 and 416 in a directionperpendicular to the plane of the figure. In either case, the snapsprings 418 and 412 are preferably incorporated within the plasticprotective jacket of the battery during the manufacturing process.

To make it easier to put the device on and to take it off, analternative embodiment (not shown) provides for one end of the batteryto be hinged to the underside of the scanner/laser pointer. The otherend is secured by an easily-releasible clasp. To put the device on, orto take it off, the user merely releases the clasp and hinges thebattery away from the underside of the scanner/laser pointer.

FIG. 10 shows a storage box 500 which is suitable for use with thesystem shown in FIG. 1A. The box comprises a base portion 502 and alockable hinged lid portion 504. Within the base portion 502 there is afirst recess 506 for storing the watch 7 (FIG. 1A) and a second recess508 for storing the ring 1 (also FIG. 1A). In addition to providingconvenient and secure storage, the box 500 incorporates a batterycharger (not shown) to recharge any battery that may be incorporatedwithin the watch 7 and/or the ring 1. To that end, when the watch isplaced within the recess 506, its rear surface comes into contact withelectrodes 510. Likewise, when the ring is placed in the recess 508,with the band portion pushed down into a slot 512, it comes into contactwith further electrodes (not shown). Power is provided to theseelectrodes via a main supply which is plugged into a socket 514 on theoutside of the box. The electrodes become live, thereby recharging thebatteries (for example overnight) when the lid 504 is closed, therebyclosing a microswitch 520.

In some embodiments, the watch 7 of FIG. 1A may be used to store data,and may accordingly have a memory chip inside it. When the watch isplaced in the recess 506, an electrical contact on its rear surfaceabuts a corresponding contact 522 at the base of the recess. The datawithin the watch may then automatically be downloaded, or downloaded onrequest, via a data socket 516 to an external computer (not shown).

Self Triggering Mode

Another key feature of the present invention is to implement a varietyof adaptable “self triggering” or “object sensing” modes of operationthat eliminate the need for a manual trigger switch, and also optimizethe turning on of the scanning and bar code reading operation fordifferent ergonomic implementations—fixed mount, hand-held (includinghand-supported), ring or finger-mounted, body mounted, etc., all ofwhich may require different “turn on” conditions for the userapplications envisioned. Reference is first made to U.S. Pat. No.5,280,162 of the present assignee for background information describinga scanning system operable in a “sleep” mode including object sensing,and a “scanning” mode after sensing an object in the scanning field.

Another prior art design uses an infrared LED which is blinking at ahigh frequency. A photo detector is connected to analog circuitry thatresponds to signals at the frequency at which the LED is blinking. Whenan object with a bar code is placed in front of the scanner, someinfrared light is reflected back to the detector. The circuit respondsto this by sending a “Trigger” signal to the decoder, which initiatesscanning.

Such prior art systems have several drawbacks. The signal detectorcircuitry adds costs and complexity to the scanner. The LED alsoconsumes power, which is a drawback in battery powered applications. Thesensing range varies depending on the size and color of the object beingsensed, and it is subject to false triggering which can cause accidentalreading and wastes power.

In other prior art self-triggering designs, the laser is turned on forone scan and off for three scans. If during the scan with the laserturned on something resembling a bar code is detected somewhere in thescan field, the laser stays on until either a symbol is decoded or apredetermined time has elapsed. The scanner then resumes blinking thelaser.

This is an improvement over the other prior art design since it adds noadditional circuitry to the scanner. It is less likely to false triggerbecause it only turns on when real bar codes or at least things thatlook like bar codes are detected, and its range inherently matches therange of the scanner, regardless of the size and color of the item beingscanned.

However, the blinking laser is visually annoying to some users. Sensingcan be sluggish because it can take as much as three scan periods todetect an object, because the scanner cannot sense symbols when thelaser is off. Accidental reads are still possible because it can sense asymbol anywhere along a wide scan line. Power is still consumed by thelaser when it is turned on, and by the decoder which performs a controland monitoring function, and which therefore must be kept turned on tocontrol the blinking and sensing.

Still another prior art design has the laser turned on all the time.Such design is usually not commercially useful since it would toorapidly use up the laser's limited life. It would also heat up the laserand the interior of the scanner housing which would further shorten thelaser's life. It would also use a substantial amount of power. Exceptfor the decoder, the laser uses more power than any other component of ahand-held scanning item.

The blinking laser mode is only practical with a very long lived motor,as it requires the motors to run continuously. These motors will notwear out and use so little power that they do not heat up the interiorof the scanner.

It has been determined from experimental measurements that blinking thelaser on for one out of four scans keeps it cool enough that itslifetime will be satisfactorily long, assuming adequate heat sinking andminimum heat generation by other circuitry.

The present invention provides a way to have the laser turned on only25% of the time by turning it on every scan, but only for 25% of thescan period. In scanners that run typically at thirty-six scans persecond, each scan takes 27.7 milliseconds, so if the laser is turned onfor only 6.9 milliseconds in each scan, it will be on 25% of the time.The laser will then have the same lifetime as it would in a scanner thatturns the laser on for one out of four scans. The figure 25% is chosenas an example in our discussion, but may be any appropriate percentageof the particular application envisioned.

Turning to the Figures, FIGS. 11a and 11 b are schematic representationsof laser beam scanning patterns as is known in the prior art, whereinthe laser is turned on for the entire duration of a scan. FIG. 11b issimilar to that in U.S. Pat. No. 4,933,538, wherein t₂ is a later timethan t₁. FIGS. 11c, 11 d and 11 e are schematic representations of laserbeam pulsing patterns according to the present invention, wherein thelaser is turned on for a fraction of the duration of a scan. In thepreferred embodiment of FIG. 11c, the laser should be turned on in themiddle of the scan time so the scanner user will see a short scan linethat occurs every scan, instead of a long line every fourth scan. Theshort line will not appear to blink because thirty-six scans a second isabove the frequency at which the human eye can perceive the flickeringof a light. Flickering is quite visible with existing bar code readersthat blink only nine times per second. The visually persistent shortline serves as an aiming indicator useful for pointing a hand-heldscanner at a targeted symbol prior to reading the symbol.

Some care should be taken to assume that the laser is turned on in thecenter of the scan in both scanning directions. If the blinking iscontrolled by a microprocessor, preferably the same one that is used fordecoding, this is easily accomplished, as described below.

The scan element is typically a generally planar mirror movable by thescan element driver, which is typically a motor. A microprocessorcontrol generates driving signals for energizing the motor to move themirror at selected times and for desired durations. The light beamgenerated by the laser is directed at the mirror for reflectiontherefrom toward the targeted symbol to be read.

If the motor is not energized at a particular time, then the mirror willbe stationary, and the light beam reflected off the stationary mirrorwill form a light “spot” on the targeted symbol. If the motor isenergized for a short time duration, then the light beam reflected offthe moving mirror will form a “short line” on the targeted symbol. Ifthe motor is energized for a long time duration, then the light beamreflected off the moving mirror will form a “long line” on the targetedsymbol.

In the embodiment of FIG. 11d, the spot and short line formationsalternate cyclically during a scan period. The scan period commences andends at opposite scan end-limiting positions. Thus, in FIG. 11d, thereare three spots and two lines that are formed on the targeted symbolduring each scan period. The laser is not turned on for the entire scanperiod as in prior art scanners, but instead, is turned on for afraction of the scan period, thereby minimizing laser usage and, at thesame time, providing a visually persistent aiming image on the targetedsymbol. The successive aiming images provides an operator with multiplechances to aim the scanner at the symbol.

In the embodiment of FIG. 11e, a first spot is followed by a first shortline and then, in order, by a second spot, by a second short line, by athird spot, by a long line, and finally by a fourth spot—all during asingle scan period.

Other patterns of spots, short lines, and long lines are contemplated bythis invention, the change or “blinking” between such light formationsbeing particularly visually effective in accurate and rapid aiming.

If a scan motor, such as described in U.S. Pat. Nos. 5,212,627 and5,367,151, that runs at its own natural frequency is used, the blinkingmust be synchronized to the motor because the motor frequency varies alittle bit from one motor to another. These patents illustrate apreferred scan motor design for use with the present invention. This canbe done using the start of scan (S.O.S.) signal that is provided by themotor drive circuitry. The S.O.S. signal is derived from a feedbacksignal that is provided by the motor drive circuitry. The S.O.S. signalis high when the motor is traveling in one direction and low when it istraveling in the other. High to Low or Low to High transitions occurwhen the motor changes direction at the end of each scan.

The laser turn-on can be controlled as set forth in the timing diagramof FIGS. 12a, 12 b, and 12 c. FIG. 12a is the timing diagram of theembodiment of a laser beam pulsing pattern corresponding to FIG. 11c;and FIGS. 12b and 12 c are timing diagrams of alternative embodiments ofthe laser beam pulsing pattern. There are two types of timing errorsthat occur with the S.O.S. signal that should be taken into account whenthe S.O.S. signals are used to synchronize the laser blinking with themotor. The scans are not always symmetrical. Sometimes, for example, amotor takes twenty-seven milliseconds to scan left to right andtwenty-eight milliseconds to scan right to left. In addition, the S.O.S.transitions typically do not correspond exactly with the time that themotor reverses direction. The S.O.S. transitions are typically delayedby about one or two milliseconds, depending on the sensing circuitryused.

These variations can be corrected by the microprocessor that controlsthe blinking as follows. When power is first applied to the scannersoftware, the decoder measures the scan time in each direction using theS.O.S. signal. For each direction, the decoder then calculates the valueequal to three eighths of the measured scan time. The software routinethen subtracts from this value the number of milliseconds by which theS.O.S. signal lags behind the actual turn around moment of the motor(typically 1-2 milliseconds). The signal lag number is determined fromboth the design of the particular type of motor and drive circuit beingused. The signal lag will be approximately the same for all units of agiven design.

When a start of scan transition occurs, the decoder waits the amount oftime calculated above for the particular scan direction that isbeginning; i.e., three eights of the measured scan time adjusted by thesignal lag number. It then enables or turns on the laser for 25% of themeasured scan time. This process is repeated every time the S.O.S.signal transitions, indicating the start of a new scan. Additionalcorrections for such things as slow response of the laser controlcircuitry can be made as necessary.

When all of the above is properly implemented, a scan line that isshorter than the full scan line will be visible that is centered withrespect to the full scan line. This short line will be illuminated inboth left to right and right to left scans. Although the laser is on foronly 25% of the scan time, the visible scan line will be longer than 25%of the total scan line because the beam moves fastest in the center ofthe field. Experiments show that, in a typical scanning system with aresonant motor, the short scan line will be about 33% as wide as thefull scan line, even though the laser is only on 25% of the time.

As described above, the present invention provides an optical scannerfor reading bar code symbols on a target at a distance from the unit,including scanning element for generating a laser beam directed toward atarget producing a pulsed relatively short image line on the targetplane during a first time period and a substantially continuous wideangled laser beam that sweeps an entire symbol during a second timeperiod for reading the symbol, and a detection element for receivingreflected light from such symbol to produce electrical signalscorresponding to data represented by such symbol. The first and secondtime periods cyclically repeat during normal operational use.

This system is used to sense symbols as follows. When power is appliedto the scanner it begins blinking the laser as described above. The useraims the visible shortened scan line at the symbol to be scanned, or ifthe scanner is stand mounted, positions the symbol under the visibleshortened scan line.

When the scan line crosses a symbol or part of a symbol, the scanner cantry to decode the symbol. If it fails, the laser can be turned on forthe full scan time for the next few seconds or until a decode hasoccurred, at which time the short scan line returns. Multiple decodes ofthe same symbol can be prevented by programming the decoder not todecode the same symbol again until it is out of view for a while(typically 0.5 to 1 second).

This self triggering element has the following advantages. It does notappear to flicker because it blinks above the flicker perceptionfrequency. It reduces the possibility of accidental triggering becauseit will only sense an object that looks like a bar code and only when itis centered in the scan field. It adds nothing to the circuit complexityand provides easier aiming than an invisible Infra-Red Sensor. It isusable for hand-held, fixed mounted, and wearable scanners. It is fasterresponding than blinking the laser one out of four scans because it cansense a symbol every scan, as opposed to every fourth scan.

Additional refinements can be used to further reduce power consumption.If necessary, the laser can be turned on for 25% of a scan time everyother scan or even every third or fourth scan. This may result invisible flicker, but it might be acceptable in battery poweredapplications. In addition, the laser can be modulated at a highfrequency during the sensing period. This can reduce its powerconsumption by half during its “On” time.

With these measures, the scanner (excluding decoder) can operate in itssensing mode at an average current of less than ten ma. This assumesthat one of the commercially available visible laser diodes that operateat around thirty ma is used. If it is blinked on for 25% of every fourthscan its average current draw will be 1.875 ma. If it is modulated at50% duty cycle during its “On” time, its average is 0.937 ma. Currentresonant motors operate at 0.5 ma. Analog circuitry includingamplifiers, digitizer, motor control, and laser regulator have beenbuilt that use less than 8 ma for a total of 9.43 ma (all at 3 to 5volts).

Sometimes it is desirable to have a triggerless scanner that has noon-board decoder. Ideally, it should be compatible with existingdecoders that are made for hand-held scanners. Current decoders containsoftware to control the laser, including any laser blinking. This makesit impossible to connect triggerless scanners or to use Intellistandswith decoders. This problem can be avoided if an inexpensivemicroprocessor is used to control laser blinking and symbol sensing in adecoderless scanner.

There are small microprocessors available that can perform the blinkingcontrol as described above. The same microprocessor that blinks thelaser can monitor the output of the digitizer during the time the laseris blinked on. If the microprocessor detects a sufficient number ofelements being digitized to indicate that a symbol might be present, itcan generate a simulated trigger pull signal that will signal the remotedecoder that a symbol is present, just as if someone pulled a trigger.When the symbol is removed, the “trigger” will be automaticallyreleased.

If 25% is used as an appropriate blink duty cycle, higher duty cyclescan of course be used if long lived lasers are used or lifetimerequirements are modest. Scanners that never operate in hot environmentscan also operate at higher duty cycles. Lower duty cycles can be used toreduce power consumption or when the scanner is to operate in a hotenvironment.

The duty cycle can be user selectable by programming the reader, or byscanning special bar codes. This makes it easy to match the scanner tothe environment.

FIG. 12d shows a timing diagram of an alternative embodiment of thelaser beam pulsing pattern occurring in a decoderless scanner. In thisembodiment, the laser and the driver, or motor, for moving the scanningelement are separately controlled by a microprocessor. Themicroprocessor directly clips the scan beam by toggling a laser enablesignal during a driver scan cycle. In this way, the laser turns on afterthe driver begins the scan cycle and turns off before the scan cycleends.

FIG. 13 is a block diagram of one possible system relating to thisalternative embodiment. Laser 1310 directs a light beam onto mirror 1320in response to a laser enable signal from microprocessor 1330. Mirror1320 deflects the light beam to provide a scanning beam. Driver 1340,which may be in the form of a motor, selectively oscillates mirror 1320in response to an S.O.S. (start of scan) signal from microprocessor1330, thereby causing the light beam to be scanned along a scan path1350.

As shown in FIG. 12d, driver 1340 begins a scan cycle in response toeach transition in the S.O.S. signal from microprocessor 1330. During ascan cycle, driver 1340 directs mirror 1320 along scan path 1350. Afterdriver 1340 begins the scan cycle, microprocessor 1330 outputs a laserenable signal to turn on laser 1310 to emit the light beam forilluminating a target to be read, such as target 1360. Laser 1310continues to emit the beam until microprocessor 1330 terminates thelaser enable signal prior to the end of the scan cycle; i.e., before thenext transition in the S.O.S. signal which causes driver 1340 to beginanother scan cycle.

By this arrangement, microprocessor 1330 controls laser 1310 to emit thelight beam for a portion of every scan path. When an S.O.S. signaltransition occurs, microprocessor 1330 waits for a predetermined amountof time and then outputs the laser enable signal to turn on laser 1310.Microprocessor 1330 might control laser 1310 to emit the light beam for25% of the scan time or about 33% of the full scan path, as describedabove.

Optical detector 1370 receives the light beam reflected by target 1360and outputs a signal to a digitizer (not shown). The digitizer might beincorporated in microprocessor 1330 or might alternatively be a separatedevice. Microprocessor 1330 monitors the output of the digitizer duringthe time the laser is turned on. If microprocessor 1330 detects asufficient number of bar code elements being digitized to indicate thata target might be present, it generates a simulated trigger pull signalto inform a remote decoder that a target is present. If the remotedecoder decodes the entire target, then microprocessor 1330 continuesthe light beam pulsing pattern. If the remote decoder fails to decodethe entire target, however, microprocessor 1330 turns on laser 1310 forthe full scan time for the next few seconds or until a proper decodeoccurs, at which time microprocessor 1330 resumes the light beam pulsingpattern.

By clipping the beam electronically, average laser power is kept low.This may eliminate the requirement to lower the laser output power overthe entire scan path. Additional refinements can be used to furtherreduce power consumption. For example, the laser can be turned on for25% of the scan time every other scan or even every third or fourthscan.

Although the present invention has been described with respect toreading bar codes, including stacked, or two dimensional bar codes, suchas Code 49, PDF 417 and similar symbologies, it is conceivable that themethod and apparatus of the present invention may also find applicationfor use with various machine vision or optical character recognitionapplications in which information is derived from other types of indiciasuch as characters or from the surface characteristics of the articlebeing scanned.

In all of the various embodiments, the elements of the scanner may beassembled into a very compact package that allows the entire scanner tobe fabricated on a single printed circuit board or as an integralmodule. Such a module can interchangeably be used as the laser scanningelement for a variety of different types of data acquisition systems.For example, the module may be alternately used in a finger ring,hand-held or body-mounted scanner, a table top scanner attached to aflexible arm or mounting extending over the surface of the table orattached to the underside of the table top, or mounted as a subcomponentor subassembly of a more sophisticated data acquisition system. Controlor data lines associated with such components may be connected to anelectrical connector mounted on the edge or external surface of themodule to enable the module to be electrically connected to a matingconnector associated with other elements of a data acquisition system.

An individual module may have specific scanning or decodingcharacteristics associated with it, e.g. operability at a certainworking distance, or operability with a specific symbology or printingdensity. The characteristics may also be defined through software or bythe manual setting of control switches associated with the module. Theuser may also adapt the data acquisition system to scan different typesof articles or the system may be adapted for different applications byinterchanging modules on the data acquisition system through the use ofa simple electrical connector.

The scanning module described above may also be implemented within aself-contained data acquisition system including one or more suchcomponents as a keyboard, display, printer, data storage, applicationsoftware, and databases. Such a system may also include a communicationsinterface to permit the data acquisition system to communicate withother components of a local area network or with a telephone exchangenetwork, either through a modem or an ISDN interface, or by low powerradio broadcast from the portable terminal to a portable or stationaryreceiver or base station.

It will be understood that each of the features described above, or twoor more together, may find a useful application in other types ofscanners and bar code readers differing from the types described above.

For example, a hand-held scanner 600 is depicted in FIG. 14. Scanner 600includes a handle 602 for gripping by a user, a body 604 supported bythe handle, a trigger 606, either of the single-position or thedouble-position type, a window 608 through which the laser beam and/orlight reflected from a bar code symbol pass, and a pair of support feet610, 612 for supporting the scanner when the scanner is laid on acountertop or like support surface.

An omni-directional scan line pattern generator 614, as depicted in FIG.15, is mounted within the scanner 600 and is operative for generating anomni-directional, multiple, scan line pattern or, when converted asdescribed below, a single line scan pattern. The generator 614 includesa drive motor 616 having an output shaft 618 on which a mirrored elementor polygon 620 is mounted for joint rotation in the circumferentialdirection of the arrow 622 about axis of rotation 632. The element 620can have any number of mirrored sides. In the preferred embodiment, theelement 620 is a square having four mirrored sides or inner mirrors 624,626, 628, 630. Each inner mirror is a generally planar, front surfacereflecting mirror that is slightly inclined relative to the axis 632.The inner mirrors are preferably of the same size and are equiangularlyarranged around the axis 632.

The generator 614 further includes a plurality of outer, beam-folding orcrown mirrors 634, 636, 638, 640, 642, which are also equiangularlyarranged around the axis 632 in an annulus surrounding the motor 616.Any number of outer mirrors may be employed. In the preferredembodiment, there are five outer mirrors. Each outer mirror is inclinedrelative to the axis 632.

A light source, preferably a semiconductor laser 644, is mounted withinthe scanner and emits a light beam 646 to the element 620 for successivereflection off the inner mirrors during rotation of the element. Eachcomplete revolution of the element generates, in the preferredembodiment, four scan lines in generally mutual parallelism. The laserbeam 646 may be directed through an optical train prior to reaching thepolygon, but this has been omitted from FIG. 15 for the sake ofclarifying the drawing.

The laser beams reflected off the inner mirrors are, in turn,successively directed to, and reflected from, the outer mirrors throughthe window 608 toward a bar code symbol to be read. Each outer mirrorgenerates a set of the scan lines. The different angles of inclinationof the outer mirrors generates intersecting sets of the scan lines. Inthe preferred embodiment, there are five intersecting sets of four scanlines each. The resultant omni-directional, multiple scan line patternprovides a very effective coverage over the symbol with a highlikelihood that at least one of the twenty scan lines will extend acrossall the bars and spaces of the symbol to be read.

In accordance with this invention, it is desired to convert thisomni-directional, multiple line scan pattern to a single scan line byintermittently operating and de-energizing the light source 644. Thesingle scan line is useful as an aiming beam or, in some cases, can beused as a scanning beam to read the symbol. As an aiming beam, thesingle scan line has sufficient visibility to be seen by the user.

The intermittent operation of the light source can be achieved in manydifferent ways. It is currently preferred to key the position of theelement 620 on the motor shaft 618 so that only one of the innermirrors, e.g., inner mirror 630, and only one of the outer mirrors,e.g., outer mirror 642, are employed to generate the single scan line.The motor shaft 618 is provided, as shown in FIG. 16, with an axialprojection or spline 648 that receives, and fits into, a complementaryaxial groove within the element, thereby not only enabling both theshaft and the element to rotate together, but also to determine a fixedangular position that serves as a known reference position from whichthe position of a leading edge 650 of the inner mirror 630 isdetermined. The light source 644 is turned on when the light beam 646passes the leading edge 650, and is turned off automatically when thelight beam passes the trailing edge 652 of the inner mirror 630. Thelight source 644 is maintained off until the light beam 646 again passesthe leading edge 650.

In the preferred embodiment, the element is rotated at a given constantspeed of 3600 rpm±50 rpm, and completes one revolution in a known totaltime. The time it takes for the light beam to traverse the inner mirror630 is about one-twentieth of the total time that it takes for thepolygon to make a complete revolution. Hence, a timer can be used toautomatically shut down the light source after a known time after theleading edge 650 is detected.

The leading edge 650 can be detected by a Hall effect sensor 654 mountedwithin the motor and cooperating with a magnet 656 mounted in theelement. Each time the magnet 656 passes the sensor 654, an electricalpulse signal is generated. This pulse signal is conducted to a controlcircuit including a microprocessor 658 that generates an output controlsignal to energize a power supply 660 that supplies power to the lightsource 644. At the same time, a timer 662 is actuated and, after theelapse of a predetermined time, the power supply 660 is de-energized,and the light source is turned off.

Rather than using a Hall effect sensor, a light absorbing black stripe631 can be applied over the leading edge 650. During rotation of theelement 620, the moving light beam 646 is swept across the symbol, andlight is reflected from the symbol. Some of the reflected lightre-enters the scanner through the window 608 and is detected by a systemphotodetector. The system photodetector generates an analog signalcorresponding to the symbol being swept. This analog system is digitizedand decoded as is well known in this art. Upon detection by the systemphotodetector of an abrupt drop in the intensity of the reflected light,the black stripe 631 and the leading edge 630 are reliably detected. Asbefore, the detection of the leading edge is employed to cause themicroprocessor 658 to energize the laser power supply 660.

Still another way of detecting the leading edge is to mount an auxiliarylight source, such as a light emitting diode 651 on a printed circuitboard 653 situated above the element 620. A highly reflective dot 655 isapplied on an upper surface of the element 620, and is operative toreflect light emitted by the diode 651 to a photodiode 657 located onthe circuit board 653 alongside the diode 651. The photodetector 657detects the presence of the dot 655 and generates an output pulse signalwhich precisely locates the position of the leading edge 650 during eachrotation of the element 620.

Still another technique for locating the leading edge 650 is to use acounter. The counter begins to count at the time that the leading edgepasses a known reference point on the shaft, and stops counting at aknown time thereafter. The output of the counter is used to control themicroprocessor and, in turn, the laser power supply and the lasersource.

The scanner 600 is operated in any one of several different modes. If afirst mode, the generator 614 is automatically and constantly operatingto generate the multiple line, omni-directional scan pattern describedabove. In order to change the scan pattern to a single scan line, theuser manually depresses the trigger 606, after which the microprocessorcontrols the power supply 660 to energize the laser source 644 only forso long as the laser beam 646 is traversing the inner mirror 630.

In a second mode, the user manually depresses the trigger 606 once to afirst position to initiate the generation of the multiple line,omni-directional scan pattern. In order to change the scan pattern to asingle scan line, the user manually depresses the trigger 606 either asecond time, or to a second position.

In a third mode of operation, the generator 614 is automatically andconstantly operating to generate the multiple line, omni-directionalscan pattern for as long as the scanner 600 is mounted on a stand. Inorder to change the scan pattern to a single scan line, the scanner 600is removed from the stand and the trigger 606 is manually depressed.

Any one of these three modes is selectable in advance by the user. Thedetection of the scanner 600 in the stand in the third mode isconveniently accomplished by a Hall effect sensor and a magnetrespectively mounted in the stand and the scanner. The mounting of thescanner 600 on the stand causes a signal to be generated. This signal isthen used to tell the microprocessor that the scanner is on the stand.

While the invention has been illustrated and described as embodied in itis not intended to be limited to the details shown, since variousmodifications and structural changes may be made without departing inany way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can readily adapt it for variousapplications without omitting features that, from the standpoint ofprior art, fairly constitute essential characteristics of the generic orspecific aspects of this invention and, therefore, such adaptions shouldand are intended to be comprehended within the meaning and range ofequivalence of the following claims.

We claim:
 1. An arrangement for electro-optically reading indicia,comprising: a) an energizable light source for emitting a light beamwhen energized; b) a pattern generator for moving the light beam in amultiple line, scan pattern across an indicium during a scan period in afirst mode of operation; c) a controller for converting the multipleline, scan pattern to a single scan line by intermittently operating andenergizing the light source to emit the light beam for a working timeperiod which is less than, and a fraction of, the scan period to causethe pattern generator to generate the single scan line across theindicium in a second mode of operation; d) a detector for detectinglight reflected from the indicium during one of the modes, and forgenerating an electrical signal indicative of the indicium; and e) atransmitter for transmitting the electrical signal by wirelesscommunication to a host remote from the light sources.
 2. Thearrangement of claim 1, wherein the light source is a semiconductorlaser.
 3. The arrangement of claim 1, wherein the pattern generatorincludes a mirrored element having a plurality of inner mirrors, a drivefor rotating the element about an axis of rotation, and a plurality ofouter mirrors arranged about the axis and spaced radially from the innermirrors.
 4. The arrangement of claim 3, wherein the inner mirrors areequidistantly arranged around the axis, and wherein the outer mirrorsare equidistantly arranged around the axis.
 5. The arrangement of claim3, wherein the inner mirrors of the mirrored element are successivelyimpinged by the light beam during rotation; and wherein one of the innermirrors has a leading edge and a trailing edge as considered along thedirection of rotation; and wherein the controller is operative forenergizing the light source as the light beam impinges the leading edge,and for de-energizing the light source as the light beam impinges thetrailing edge of said one mirror during rotation in the second mode ofoperation.
 6. The arrangement of claim 5; and further comprising an edgedetector for detecting the leading edge of said one mirror duringrotation in the second mode of operation.
 7. The arrangement of claim 6,wherein the edge detector includes a light-absorbing marker situated onthe leading edge of said one mirror.
 8. The arrangement of claim 6,wherein the edge detector includes a light-reflective marker situated onthe element.
 9. The arrangement of claim 6, wherein the drive includes amotor having a drive shaft, and wherein the edge detector includes aspline on the shaft and keyed in a predetermined position to theelement.
 10. The arrangement claim 6, wherein the edge detector includesa permanent magnet on the element for joint rotation therewith, and aHall effect sensor adjacent the magnet and operative for generating anoutput control signal corresponding to the location of the leading edgeas the magnet moves past the sensor.
 11. The arrangement of claim 1; andfurther comprising a housing in which the light source and the patterngenerator are mounted; and further comprising a mode selector forselecting the mode of operation.
 12. The arrangement of claim 11,wherein the pattern generator automatically operates in the first mode,and wherein the mode selector includes a manually depressable trigger onthe housing and operative, when depressed, to actuate the controller toconvert the pattern generator to operate in the second mode.
 13. Thearrangement of claim 11, wherein the mode selector includes atwo-position, manually depressable trigger on the housing and operative,when depressed to a first position, to actuate the pattern generator tooperate in the first mode, and further operative, when depressed to asecond position, to actuate the pattern generator to operate in thesecond mode.
 14. The arrangement of claim 11, wherein the housing has ahandle for hand-held use, and wherein the mode selector actuates thepattern generator to operate in the first mode when the housing is nothand-held, and includes a manually depressable trigger on the housingand operative, when hand-held and depressed, to actuate the controllerto convert the pattern generator to operate in the second mode.
 15. Anarrangement for electro-optically reading bar code symbols, comprising:a) a housing having a handle for hand-held use; b) an energizable laserin the housing for emitting a laser beam when energized; c) a patterngenerator in the housing, for moving the laser beam in anomni-directional scan pattern comprised of a plurality of intersectingsets of a plurality of scan lines across a symbol during a scan periodin a first mode of operation; d) a controller in the housing forconverting the plurality of scan lines to a single scan line byintermittently operating and energizing the laser to emit the laser beamfor a working time period which is less than, and a fraction of, thescan period to cause the pattern generator to generate the single scanline across the symbol in a second mode of operation; e) a mode selectorfor enabling a user to change the mode of operation of the patterngenerator; f) a detector for detecting laser light reflected from thesymbol during one of the modes, and for generating an electrical signalindicative of the symbol; and g) a transmitter for transmitting theelectrical signal by wireless communication to a host remote from thehousing.
 16. The arrangement of claim 15, wherein the selector includesa manually depressable switch on the housing and operative, whendepressed, to convert the operation from the first mode to the secondmode.
 17. A method of electro-optically reading indicia, comprising thesteps of: a) emitting a light beam from a light source; b) moving thelight beam in a multiple line, scan pattern across an indicium during ascan period in a first mode of operation; c) converting the multipleline, scan pattern to a single scan line by intermittently operating andenergizing the light source to emit the light beam for a working timeperiod which is less than, and a fraction of, the scan period togenerate a single scan line across the indicium in a second mode ofoperation; d) detecting light reflected from the indicium during one ofthe modes, and generating an electrical signal indicative of theindicium; and e) transmitting the electrical signal by wirelesscommunication to a host remote from the light source.
 18. The method ofclaim 17, wherein the moving step is performed by rotating a successionof inner mirrors past the light beam about an axis of rotation, one ofthe inner mirrors having a leading edge and a trailing edge asconsidered along the direction of rotation; and wherein theintermittently energizing step is performed by energizing the lightsource as the light beam impinges and passes by the leading edge, and byde-energizing the light source as the light beam impinges and passes bythe trailing edge of said one mirror during rotation in the second modeof operation.
 19. The method of claim 18; and further comprising thestep of detecting the leading edge of said one mirror during rotation inthe second mode of operation.
 20. The method of claim 17; and furthercomprising the step of selecting the mode of operation.